Depth probe for intracranial treatment

ABSTRACT

A depth probe for intracranial treatment is provided having a body that includes a distal portion with at least one aperture and at least one element, a lumen defined by the body that communicates between an opening and the aperture, and a proximal portion with at least one proximal-contact. The proximal-contact is conductively connected with the element. The lumen is preferably sized to receive an inner catheter adapted to transfer a fluid such as a drug with a tissue region within the patient&#39;s brain. The depth probe can include a connector adapted to receive a plurality of proximal-contacts. A depth probe is disclosed that has a distal portion with an aperture and element, a lumen communicating between an opening and the aperture, and an inflatable balloon secured upon its distal portion. The balloon is adapted to seal upon inflation the tract created by the probe when inserted into the brain.

RELATED APPLICATION

This application claims the benefit of U.S. patent application Ser. No.10/423,587, filed on Apr. 25, 2003.

FIELD OF INVENTION

The present invention relates to instrumentation utilized forintracranial treatment and, in particular, to depth probes utilized forintracranial treatment.

BACKGROUND OF THE INVENTION

Movement disorders such as epilepsy and Parkinson's disease have beenestimated to affect some 1-2% of the developed world's population and upto 10% of people in underdeveloped countries. Currently, approximately75% of those who suffer from movement disorders are responsive in somedegree to drugs.

Electrical stimulation has also been utilized to treat some movementdisorders. In the treatment of epilepsy, studies have been performed inwhich awake patients undergoing temporal lobe surgery underwent corticalstimulation. Such stimulation of the visual and hearing areas of thebrain reproducibly caused the patients to experience visual and auditoryphenomena. This discovery was made possible by the identification thatcertain brain subregions served specific functions, such as sight,hearing, touch and movement of the extremities and proved that directelectrical stimulation of the brain regions could cause partialreproduction or suppression of the functions.

As suggested by these results, it is known that certain types oftreatment of specific portions of the brain are able to suppress certainunwanted behavior which results from movement disorders. This behaviormay include seizures such as those suffered by epileptics. However, thestudies faced a major problem in that there was an inability toprecisely electrically stimulate very small volumes of the brain.

The advent of needle-shaped penetrating depth electrodes helped toovercome this obstacle faced by electrical stimulation. Depth electrodescan be placed within the brain tissue itself, enabling optimal surfacecontact with elements of the brain that are targeted for stimulation.This allowed for safe, chronic electrical stimulation of very smalldiscrete volumes of brain.

In treatment, electrical stimulation has been used with the recordingand analysis of changes in brain activity to predict the occurrence ofepileptic seizures. The time of onset of such seizures is oftenpredictable by neural discharge monitoring, even when the exact causalnature of precipitating dysfunction is not understood. Electrodes havebeen used to obtain signals representative of current brain activityalong with a signal processor for continuous monitoring and analysis ofthese electrical signals in order to identify important changes or theappearance of precursors predictive of an impending change.

While the electrical stimulation of brain tissue has been somewhateffective in the treatment of migraines, epilepsy and other neurologicalproblems, patients often experience diminishing returns with suchtreatment. Furthermore, because each patient reacts differently toelectrical stimulation, substantial time must be spent to determine thespecific amplitude, frequency, pulse width, stimulation duration, etc.which may result in effective treatment. In addition, such parametersoften require continual adjustment in order to remain effective.

Improved intracranial monitoring devices have been shown to facilitatetreatments of movement disorders. Monitoring is typically performed byinstruments which are inserted into the brain at different locations oralong different tracks. Other systems employ a single device which mustbe removed and reinserted to provide for delivery of multiple drugs oruse of different electrical devices.

Since the introduction of probes or other similar devices into the brainis common in many surgical procedures today, there are a variety ofprobes available. Such probes typically include ports for drug deliveryor electrical, chemical, electrochemical, temperature and/or pressurecontacts which enable the observation and analysis of the brain state orcontacts providing stimulation. These ports and contacts must typicallybe positioned at specific points or regions in the brain.

Probes used in intracranial penetration are typically fabricated so thattheir introduction to the brain is as minimally traumatic as possible.In addition to being minimally traumatic during insertion, certaininserted probes must also be able to remain implanted without causinginjury through unintended movement. In some uses, a probe may beimplanted and remain in the patient's brain for weeks or longer. Changesin the positioning of the probe often occur during placement or duringsuch extended periods. Therefore, the probe must be capable of preciseplacement and as bio-compatible as possible. In response to theserequirements, state of the art intracranial probes are typically thin,flexible pieces with smooth surfaces to minimize the amount of braintissue contacted and to minimize damage to contacted brain tissue.

While such thin, flexible probes are sufficiently bio-compatible, theyare delicate and often difficult to insert along specific trajectoriesor lines of insertion. During typical implantation, a surgeon feeds theprobe into the brain through an aperture in the skull. In this process,the surgeon has very little control over the distal end of the probe. Inorder to provide more rigidity to the probe to overcome this problem, aremovable stylet may be inserted into the probe before implantation.Still, veering from the intended line of insertion is not altogetherprevented by introduction of a stylet to the probe.

There is a continuing significant need in the field of intracranialtreatment, particularly with insertion of probes into the interior ofthe brain, for improvements in accuracy of insertion and avoidance ofinjury, while retaining efficiency and ease of use.

In addition, there is a need in the field of intracranial treatment tominimize the invasiveness of intracranial treatment and to reduce thenumber of instruments which penetrate brain tissue or the number oftimes a single instrument must penetrate brain tissue.

Furthermore, there is a need in the field of intracranial treatment toprovide the ability to precisely locate the position of a probe duringinsertion to ensure proper positioning.

OBJECTS OF THE INVENTION

It is a primary object of the invention to provide an improved depthprobe for intracranial treatment of a patient that overcomes some of theproblems and shortcomings of the prior art.

Another object of the invention is to provide a novel depth probe thatis simple in structure and operation in order to facilitate intracranialprocedures.

Another object of the invention is to provide an exceptional depth probehaving a body adapted to avoid extensive trauma to and scarring of braintissue.

Another object of the invention is to provide an excellent depth probehaving a body that includes contacts for stimulation and/or formonitoring of the brain.

Another object of the invention is to provide a desirable depth probehaving a lumen for receiving and guiding an inner catheter for thedelivery of a drug to targeted brain tissue and that can remain inposition when the inner catheter is removed, thereby permitting repeatedinsertions of different inner catheters without extended contact withbrain tissue during insertion.

Another object of the invention is to provide an exceptional depth probethat provides an attached connector conductively connected to aplurality of monitoring and sensing elements for efficient and effectivetransmission of readings from the elements to external analysis andcontrol devices.

Yet another object of the invention is to provide a novel depth probehaving a distal portion provided with an inflatable balloon capable ofsealing off the insertion tract formed by the probe to prevent a drugbeing introduced into the brain by the probe from migrating back throughthe tract and further allows for the monitoring of cellular functionwithin the brain prior to and after introduction of the drug.

SUMMARY OF THE INVENTION

The invention is for a depth probe utilized to provide intracranialtreatment of a patient. The depth probe comprises a body having a distalportion with at least one aperture and at least one element, a lumendefined by the body that communicates between an opening and theaperture, and a proximal portion with at least one proximal-contact. Theproximal-contact is conductively connected with the element. The term“conductively connected” is meant to include a connection via a lead inthe form of a wire or fiber-optic bundle for the transmission ofelectrical and/or optical signals.

A number of highly preferred embodiments have the lumen sized to receivean inner catheter adapted to transfer a fluid with a tissue regionwithin the patient's brain. In other embodiments, the body is made fromsubstantially inflexible material.

One preferred embodiment finds the opening on the body having a taperedfitting so that a pumping instrument can be connected to the probe atthe fitting for the transfer of a fluid with a tissue region of thepatient's brain. Much preferred is where the opening is at the proximalend of the body and coaxial with the lumen. Also preferred is where theaperture is in axial alignment with the lumen.

In another desirable embodiment, the distal end of the probe is closedand the aperture is spaced away from the distal end along the distalportion. More desirable is where the body has at least first and secondapertures in communication with the lumen, each aperture being spacedaxially along the distal portion. Highly desirable is where the probehas first and second apertures communicating with the lumen that arespaced radially about the body's axis along the distal portion.

In certain preferred cases, the element is a contact that can provideelectrical stimulation to tissue regions within the patient's brain.Also desirable is where the element is a contact that monitors activity,preferably electrical activity, within the patient's brain. Moredesirable is where the probe has a plurality of contacts spaced axiallyalong its distal portion, each of these contacts being a macro-contactthat collars, i.e., circumscribes, the body. Highly desirable is wherethe contact is a micro-contact and preferably where the probe has aplurality of micro-contacts spaced axially and radially along its distalportion.

Another appreciated embodiment finds the element to be a sensor. Muchpreferred is where the sensor senses chemical activity within the brain.Another element found desirable is where it is a location marker thatallows the position of the distal portion of the probe to be identifiedwhen it is inserted into the brain. This embodiment is especiallydesirable when the marker is adapted to be identified, i.e. seen, undermagnetic resonance imaging.

One very preferred example of this invention is where there are aplurality of proximal-contacts and a connector adapted to receive theseproximal-contacts is secured to the body. It is desirable that each ofthese proximal-contacts be in electrical communication with amicro-contact. More desirable is where the connector extends outwardfrom the body and has a housing formed to position the proximal-contactsin a linear array. The connector in this embodiment has a lead-conduitextending from this housing that connects it to the body of the probe. Ahighly preferred embodiment finds the connector as being firmly attachedto the body.

Another highly desirable embodiment is where the proximal portion of thebody has a first diameter and its distal portion has a second diametersuch that the second diameter is less than the first diameter. Havingthis structure, the degree of contact with the tissue region by the bodyis reduced when the probe is inserted into the brain.

Another interesting aspect of this invention finds a depth probecomprising a body having a distal portion with at least one aperture andone element, a lumen defined by the body that communicates between anopening and the aperture, and a conduit extending from its proximalportion to an inflatable balloon secured upon its distal portion. Muchdesired is where the balloon is inflatable with at least one drug andthe balloon is formed from a material permeable to this drug so that thedrug can be introduced into the tissue region through the balloon. Alsopreferred is where the balloon is adapted to seal upon inflation thetract created by the probe upon its insertion into the brain.

A most desirable embodiment has the balloon positioned along the distalportion of the body at a point proximal to the aperture. Highlypreferred is where the balloon is positioned along the distal portionand is also proximal to the element on the probe.

In a very appreciated example, this probe also includes at least oneproximal-contact along a proximal portion at its proximal end. Theproximal-contact is conductively connected with the element through alead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred depth probe having aconnector extending outward from the body in accordance with thisinvention with cut-away sections to reveal and dashed lines to representotherwise unseen internal features.

FIGS. 2A and 2B are perspective views of the distal portions ofalternate preferred depth probes in accordance with this invention withdashed lines to represent otherwise unseen internal features.

FIG. 3 is a perspective view of another preferred depth probe inaccordance with this invention receiving an inner catheter with cut-awaysections to reveal and dashed lines to represent otherwise unseeninternal features.

FIG. 4 is a perspective view of an alternate embodiment of the depthprobe having a connector attached to the body in accordance with thisinvention with a cut-away section.

FIG. 5A is a perspective view of a preferred depth probe having aballoon shown deflated in accordance with this invention with cut-awaysections to reveal and dashed lines to represent otherwise unseeninternal features.

FIG. 5B is the distal end of the depth probe of FIG. 5A showing theballoon inflated with cut-away sections to reveal and dashed lines torepresent otherwise unseen internal features.

FIG. 6 is a schematic view illustrating the depth probe of FIGS. 5A and5B positioned within the brain.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The figures illustrate preferred embodiments of an improved depth probefor intracranial treatment of a patient in accordance with thisinvention. FIG. 1 is a perspective view of depth probe 10 having anelongated, tubular body 12 extending from proximal end 14 to distal end16. Body 12 preferably has a diameter between about 0.6 and 3.0millimeters, most preferably about 1.0 millimeter.

As seen in FIG. 1, body 12 includes elements 18 secured to distalportion 20 at distal end 16. Body 12 is also provided with lumen 22extending from opening 24 at proximal end 14 and in communication withaperture 26. Lumen 22 is a tubular channel extending for some lengthwithin body 12, preferably having a diameter of 0.5 millimeters or less.Body 12 is open at distal end 16 to form aperture 26. Opening 24 andaperture 26 are coaxial with lumen 22 along central axis 28 of body 12.

Elements 18 are conductively connected by leads 30 (seen in FIG. 1running alongside lumen 22) to proximal-contacts 32. Leads 30 can be inthe form of electrical wiring or a fiber-optic bundle. Proximal-contacts32 are mounted along proximal portion 34 of body 12. When depth probe 10is inserted into the brain, proximal-contacts 32 remain outside of thepatient. Proximal-contacts 32 are preferably formed from stainless steelor similar alloys or materials that are non-corrosive conductors andthat can endure sterilization.

Depth probe 10 can be substantially flexible, formed from bio-compatiblematerials such as polyurethane, silicone, or polyimide. Body 12 can alsobe in the form of a cannula where body 12 is made from a substantiallyrigid material that is preferably MRI safe/compatible. Such preferablematerials are platinum, titanium, polyimide-coated glass, and othernon-ferrous alloys. During surgery, when in the form of a cannula, depthprobe 10 may be used with a stereotatic frame or a frameless guidancesystem to accurately position the catheter within the brain.

As seen in FIGS. 2A and 2B, preferred embodiments of depth probe 10 canhave a closed distal end 16 and a plurality of apertures 26, eachaperture 26 in communication with lumen 22. Apertures 26 in FIG. 2A arepositioned above distal end 16 and spaced in axial alignment with axis28 along distal portion 20. Apertures 26 in FIG. 2B are shown axiallyand radially spaced about axis 28. One skilled in the art will recognizethat these configurations can also include an aperture 26 forming anopen distal end 16 as depicted in FIG. 1.

Body 12 of depth probe 10 may also include a distal portion 20 having areduced diameter as illustrated in FIG. 3. Such a configuration fordistal portion 20 allows for reduced injury to the surrounding tissueregions during the insertion of depth probe 10 into the brain.

As depicted in FIG. 3, lumen 22 is preferably sized so as to be able toreceive an inner catheter 36, i.e., lumen 22 is provided with a diameterslightly greater than the outside diameter of inner catheter 36. Afterpositioning the distal end 16 of depth probe 10 in a targeted region ofthe brain, inner catheter 36 can be inserted into opening 24 and guidedby lumen 22 to this tissue area. Inner catheter 36 can be withdrawn andreinserted or different inner catheters 36 can be inserted into depthprobe 10 without reinserting or repositioning depth probe 10. Innercatheter 36 is preferably polyimide, polyimide-coated glass or othersimilar material. Applicant notes that one such preferred catheter isdisclosed in U.S. patent application Ser. No. 10/423,587 filed byApplicant on Apr. 25, 2003, the disclosure of which is incorporated byreference herein.

Proximal end 14 of body 12 is provided with a tapered fitting 38,preferably a male luer conical fitting, to provide for a detachablefluid-tight coupling with some external device. The proximal end ofinner catheter 36 is provided with a tapered coupler 40, preferably aluer coupler that has female luer fittings at both of its ends. Taperedcoupler 40 enables inner catheter 36 to form a liquid-tight joint withdepth probe 10 when inner catheter 36 is fully inserted into lumen 22through opening 24. Coupler 40 enables inner catheter 36 to beoperatively connected by tubing to an external piece of equipment suchas a pump. One skilled in the art will recognize that inner catheter 36could also be connected to internal instrumentation having pumpingcapability. This process enables fluids such as drugs to be administeredto the brain through inner catheter 36.

Elements 18 provide for monitoring of brain activity, for stimulatingbrain tissue or for serving as a location beacon to aid in determiningthe precise position of distal portion 20 within the brain. Elements 18can take the form of contacts 42, as illustrated in FIGS. 1-6. Contacts42 comprise devices such as electrodes 44 designed to monitor brainactivity in a selected tissue region of the brain 46 through the sensingof electrical and/or electrochemical changes within the brain as well aselectrodes 48 designed to provide electrical stimulation to specificareas of the brain. Electrodes serving as contacts 42 are preferablyconstructed from platinum, platinum-iridium or other bio-compatibleconductive material. Electrodes can be macro-contacts 49 thatcircumscribe or band body 12 or micro-contacts 50 capable of measuringelectrical changes at the level of a single neuron.

Elements 18 can also can take the form of a sensor 52 as depicted inFIG. 3. Sensors 52 are designed to monitor brain activity within selecttissue regions through the sensing of electrical, electrochemical,chemical, temperature or pressure changes within the brain. Sensors 52can be electrochemical and optical transducers designed to measurechemical, pressure, temperature, cerebral blood flow and otherphysiological changes in the brain. Such devices are known in the artand are preferably less than about 2 millimeters long. Sensor 52 ispreferably in the form of a chemical sensor.

Elements 18 may further be in the form of a location marker 54 as seenin FIGS. 5A and 5B. Location marker 54 is preferably a structurecomprised of a non-ferrous material known in the art such as gold ortungsten that has an image signal intensity suitable for proton magneticresonance imaging (MRI) with most commercial machines and is alsosufficiently x-ray opaque for satisfactory imaging using computedtomographic scanning (CT) or on X-ray. Location marker 54 can also becomprised of a sensor capable of measuring voltages induced by atransmitted magnetic field that can be used to identify the position andorientation of the sensor within that field.

Elements 18 may be positioned on both the distal and proximal sides ofapertures 26 along distal portion 20 as seen in FIGS. 2A and 2B. Thisconfiguration allows for monitoring of cellular function within thetissue region of the brain 46 being targeted prior to treatment toverify the presence of diseased brain cells. Upon verification ofdiseased tissue within the targeted region, delivery of a drug or othertreatment agent can commence through depth probe 10 while monitoring ofthe tissue region 46 continues concurrently with such treatment. Thiscan have particular value in the treatment of different tissue regionsof the brain for movement disorders such as Parkinson's Disease.

FIGS. 1, 2, 5A and 5B show that macro-contacts 49 are spaced axiallyalong distal portion 20. Micro-contacts 50 can be spaced axially alongdistal portion 20 as illustrated in FIG. 4 or spaced radially aroundbody 12 as shown in FIG. 1.

FIGS. 5A and 5B illustrate a depth probe 10 having an inflatable balloon56 rigidly mounted to distal portion 20, preferably above at least oneelement 18 and at least one aperture 26. As seen in FIG. 5A, a conduit58 enters body 12 along proximal portion 34 and runs alongside lumen 22,terminating at balloon 56. Conduit 58 is preferably tubing made ofpolyurethane. Conduit 58 provides for the introduction of a fluid toinflate balloon 56 and, if necessary to withdraw fluid from balloon 56to cause deflation. Conduit 58 originates at injection port 60 that canbe operatively connected to an external device 62 such as a pump todispense or receive fluid.

As depicted in FIG. 6, following placement of distal portion 20 of depthprobe 10 within the brain, balloon 56 can be inflated to block orocclude the insertion tract 64 created during the insertion process sothat any drug administered to the brain 46 through aperture 26 cannotmigrate back through that tract. Balloon 56 is preferably made from anelastomeric material to achieve complete deflation of balloon 56 whendepth probe 10 is later withdrawn from the brain.

In certain embodiments, balloon 56 is permeable. Balloon 56 in theseembodiments can be inflated with a drug or other fluid intended to beadministered to the brain whereby the drug then permeates through thewall of balloon 56 to treat the tissue region of the brain 46surrounding balloon 56. In this manner, a drug can be introduced to onetargeted tissue region of the brain delivered by depth probe 10 throughaperture 26 at the same time the same or a different drug is transferredto another selected tissue region through permeable balloon 56. Balloon56 is preferably adapted to administering a drug to the brain slowlyover a period of time, thereby allowing for the effective introductionof the drug to the desired tissue region. This is especially desirablewhere there is a void in the particular tissue region due to somestructure such as a tumor being removed. Inflating balloon 56 within thevoid permits the medication to be more effectively transferred to all ofthe affected tissue that surrounds the outside of the balloon.

One skilled in the art will recognize that balloon 56 can be madepermeable by forming balloon 56 from a naturally porous material such aspolytetrafluroethylene (PTFE) or from an elastomeric material havingperforations formed in the wall of the balloon. The balloon wall ispreferably from 0.5 to 5.0 mils in thickness. Where the balloon wall isperforated, an array of minute perforations, each having a diameter of 5to 30 microns, is preferably uniformly spaced apart and concentratedalong a central band circumscribing balloon 56. Concentration of theperforations within such a region in the middle of balloon 56 providesfor focused delivery of the drug by limiting the area of permeation tojust the surface area of balloon 56 making conforming contact with thesurrounding brain tissue.

Tapered fitting 38 enables depth probe 10, as shown in FIG. 6, to form aliquid-tight seal with tubing or similar conduit having a female luerconnector. In this manner, opening 24 of body 12 is operativelyconnected by the tubing to an external instrument such as pumpingequipment 66. One skilled in the art will recognize that depth probe 10could also be connected to internal instrumentation having pumpingcapability. Such equipment allows fluids to be transferred to or fromtissue region of the brain 46 through any aperture 26. Drugs can then beadministered to the brain, cerebral spinal fluid can be withdrawn, orboth.

Depth probe 10, as illustrated in FIGS. 1 and 4, can also include aconnector 68. Connector 68 comprises a housing 69 mounting a lineararray 70 of proximal-contacts. Connector 68 is conductively connectedvia additional leads 30 to elements 18, preferably micro-contacts 50,along distal portion 20. Connector 68 can be rigidly mounted to body 12along its proximal portion 34 as shown in FIG. 4.

Connector 68 can also extend outward from body 12 as seen in FIG. 1.Connector 68 in this embodiment is secured to body 12 by lead-conduit72. Leads 30 that originate at connector 68 pass through lead-conduit 72before entering body 12 at a point along proximate portion 34 to proceedalong lumen 22 to the corresponding elements 18.

One skilled in the art will readily recognize that proximal-contacts 32are in an axial alignment that adapts them to being conductivelyconnected to an external connector (not shown) in operativecommunication with a computer or similar instrument having aconventional output display and monitor with a suitable power source.This enables the brain activity sensed by elements 18 linked to theseproximal-contacts to be recorded and/or analyzed and/or control overelements 18 to be exercised.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

1. A depth probe for intracranial treatment of a patient comprising: abody extending from a proximal end to a distal end and having anopening; a distal portion at the distal end having at least one apertureand at least one element; a lumen defined by the body in communicationwith respect to the opening and the aperture; and a proximal portion atthe proximal end having at least one proximal-contact, theproximal-contact being conductively connected with the at least oneelement.
 2. The depth probe of claim 1 wherein the body is made fromsubstantially rigid material and the lumen is sized to receive an innercatheter for transferring a fluid with a tissue region within thepatient's brain.
 3. The depth probe of claim 1 wherein the proximal endincludes a tapered fitting adapted to connect to a pumping instrumentfor transferring a fluid with a tissue region within the patient'sbrain.
 4. The depth probe of claim 3 wherein the body has an axis andthe opening is at the proximal end and coaxial with the lumen.
 5. Thedepth probe of claim 4 wherein at least one aperture is in axialalignment with the lumen.
 6. The depth probe of claim 4 wherein thedistal end is closed, the aperture being spaced from the distal endalong the distal portion.
 7. The depth probe of claim 6 wherein the bodyhas at least first and second apertures in communication with respect tothe lumen, the first and second apertures being spaced axially along thedistal portion.
 8. The depth probe of claim 6 wherein the body has atleast first and second apertures in communication with respect to thelumen, the first and second apertures being spaced radially about theaxis along the distal portion.
 9. The depth probe of claim 4 wherein theelement is a contact that provides electrical stimulation to a tissueregion within the patient's brain.
 10. The depth probe of claim 4wherein the element is at least one contact that monitors activitywithin the patient's brain.
 11. The depth probe of claim 10 wherein thecontact monitors electrical activity within the patient's brain.
 12. Thedepth probe of claim 10 wherein the at least one contact is a pluralityof contacts circumscribing the body and spaced axially along the distalportion.
 13. The depth probe of claim 10 wherein the contact is amicro-contact.
 14. The depth probe of claim 13 wherein the at least onecontact is a plurality of micro-contacts spaced axially and radiallyalong the distal portion.
 15. The depth probe of claim 4 wherein theelement is at least one sensor.
 16. The depth probe of claim 15 whereinthe sensor senses chemical activity within the patient's brain.
 17. Thedepth probe of claim 4 wherein the element is a location marker toidentify the position of the distal portion when the probe is insertedinto the brain.
 18. The depth probe of claim 17 wherein the locationmarker is adapted to be identified by magnetic resonance imaging. 19.The depth probe of claim 1 wherein the proximal portion includes aplurality of proximal-contacts and a connector adapted to receive theproximal-contacts is secured with respect to the body.
 20. The depthprobe of claim 19 wherein each of the proximal-contacts is in electricalcommunication with a micro-contact.
 21. The depth probe of claim 19wherein the connector extends outward from the body, the connectorhaving a housing formed to position the proximal-contacts in a lineararray and a lead-conduit extending from the housing to the body.
 22. Thedepth probe of claim 19 wherein the connector is firmly attached to thebody.
 23. The depth probe of claim 1 wherein the proximal portion has afirst diameter and the distal portion has a second diameter such thatthe second diameter is less than the first diameter to reduce the degreeof contact with the tissue region by the body when the probe is insertedinto the brain.
 24. The depth probe of claim 1 wherein the lumen issized to receive an inner catheter for transferring a fluid with atissue region within the patient's brain.
 25. A depth probe forintracranial treatment of a patient comprising: a body extending from aproximal end to a distal end and having an opening; a distal portion atthe distal end having at least one aperture and at least one element; alumen defined by the body in communication with respect to the openingand the aperture; and a conduit extending from a proximal portion at theproximal end to an inflatable balloon secured to the distal portion. 26.The depth probe of claim 25 wherein the balloon is inflatable with atleast one drug and the balloon is formed from a material permeable tothe drug such that the drug can be introduced into the tissue regionthrough the balloon.
 27. The depth probe of claim 25 wherein the balloonis adapted to seal upon inflation a tract created upon insertion of theprobe into the brain.
 28. The depth probe of claim 25 wherein theballoon is positioned along the distal portion proximal to the aperture.29. The depth probe of claim 25 wherein the balloon is positioned alongthe distal portion proximal to the element.
 30. The depth probe of claim25 wherein the lumen is sized to receive an inner catheter fortransferring a fluid with a tissue region within the patient's brain.31. The depth probe of claim 25 further comprising a proximal portion atthe proximal end having at least one proximal-contact conductivelyconnected with the element.